The present invention relates to subterranean cementing, and more specifically, in one or more embodiments, to the integration of analysis, auto-sealing, and swellable-packer elements to improve the reliability of an annular seal.
Cement compositions may be used in a variety of subterranean applications. For example, in subterranean well construction, a pipe string (e.g., casing, liners, expandable tubulars, etc.) may be introduced into a well bore and cemented in place. The process of cementing the pipe string in place is commonly referred to as “primary cementing.” In a typical primary cementing method, a cement composition may be pumped into an annulus between the walls of the well bore and exterior surface of the pipe string disposed therein. The cement composition should set in the annular space, thereby forming an annular sheath of hardened, substantially impermeable cement (i.e., a cement sheath) that may support and position the pipe string in the well bore and may bond exterior surface of the pipe string to the subterranean formation. Among other things, the cement sheath surrounding the pipe string functions to form an annular seal, preventing the migration of fluids in the annulus, as well as protecting the pipe string from corrosion.
Once set, the cement sheath may be subjected to a variety of cyclic, shear, tensile, impact, flexural, and/or compressive stresses that may lead to failure of the cement sheath. Such failure may be the result of fractures, cracks, and/or debonding of the cement sheath from the pipe string and/or the formation. Undesirably, cement-sheath failure may lead to loss of zonal isolation, resulting, for example, in the undesirable migration of fluids between formation zones. This may lead to undesirable consequences such as lost production, costly remedial operations, environmental pollution, hazardous rig operations resulting from unexpected fluid flow from the formation caused by the loss of zonal isolation, and/or hazardous production operations. Furthermore, failure of the cement sheath also may be caused by forces exerted by shifts in subterranean formations surrounding the well bore, cement erosion, and repeated impacts from the drill bit and the drill pipe.